Rubber composition and method of preserving rubber



Patented Dec. 31, 1929 PAUL G. JONES OF CUYAHOGA FALLS, OHIO, ASSIG-NOB TO THE B. IE. GOODR-ICH COM- PANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK RUBBER COMPOSITION AND METHOD OF PRESERVING RUBBER No Drawing.

This invention relates to the art of preserving rubber, either in a vulcanized or unvulcanized condition, and to rubber compositions so preserved.

It is well known that rubber gradually loses its strength and resiliency on aging, especially when exposed to light, air or heat, and that many reducing substances, such as organic nitrogen compounds, possess the property of retarding this deterioration. Among such compounds which have been employed with more or less success as ageresisters or anti-oxidants to retard the deterioration of rubber are: aniline, p-aminophenol, acetaldehyde-aniline, ethylaniline, and phenylhydrazine.

This invention, in brief, consists in treating rubber with a substance belonging to a new class of age-resisters, comprising tetrasubstituted hydrazines. These compounds, when incorporated into rubber before vulcanization, preferably from 0.1% to 5% of the age-resister being used, are far more effective in retarding the deterioration of rub-' her than the previously known substances mentioned above.

The tetra-aryl hydrazines in general may be prepared by the controlled oxidation of secondary aromatic amines. For example, if the theoretical amount of potassium permanganate in acetone solution is added to a solution of diphenyamine in acetone, the diphenylamine is oxidized to tetraphenyl hydrazine according to the following equation:

The manganese dioxide which is formed simultaneously is filtered off and the acetone evaporated. If desired the crude productmay be recrystallized from alcohol. The pure tetraphenyl hydrazine is a colorless crys- Application filed January 21, 1929. Serial No. 334,121.

It is not always necessary to purify the reaction product, since the by-products of the reaction are either themselves age-resisters, or are substantially inert. They have the efi'ect oflowering the melting point and increasing the solubility of the material in rubber, which is sometimes a considerable advantage.

Other tetra-substituted hydrazines, such as tetra-benzyl hydrazine, tetra-tolyl hydra-.

tolyl hydrazine. However, it is to be un- Y derstood that the method of preparing the tetra-substituted hydrazines is immaterial, such products in general being excellent ageresistors in rubber.

Emam'ple 1 .As a specific example of one embodiment of the method of this invention, a tire tread composition was prepared containing: blended plantation rubbers 100 parts by weight, sulfur 5.5 parts, zinc oxide 30 parts, gas black 40 parts, mineral rubber 10 parts, palm oil 5 parts, and hexa-lnethylene tetramine 0.7 5 parts. This was divided into two portions, one of which was used as a control. To the other was added 0.95 parts of the vulcanized compositions were compared by measuring their ICSPQCUVG tensile strengths and elongatio'ns before and after aging. Accelerated aging. tests were carried out in the Greer aging oven, in which samples were maintained at a temperature of 158 F., ina constantly renewed stream .of air, as well as in the Bierer-Davis bomb, in which other samples were maintained at the same temperature (158 F in an atmosphere of oxygen at a pressure of 800 lbs. per sq. In the table below T indicates ultimate tensile strength in pounds per square inch and E indicates ultimate elongation in per cent of original length. I

Aging tests of tetmphenyl hydrazine I After 7 days After 48 hours Before aging in the Gear i111) the lgierea 1 om Age-resister (0. 5%) Oven v g T E T E T E None (control) 3607 675 1976 493 804 357 Tetraphenyl hydrazine 3718 733 3389 580 2714 630 Emample 2.Tetrabe nzyl hydrazine,

O K O when tested in a rubber composition in the manner described in Example 1 above, gave the following aging results:

Aging feats of fefrflbcm'yl hydrazine After 7 days After 48 hours Before aging in the Geer iibthe Bierer- Age msister oven avls bomb '1 E T E 'l E None (control) 35 10 663 2196 470 642 263 Tetrab enzyl hydrazine 3405 G 2549 550 2089 567 Ewample 3.N,N'-cli-p-anisyl N,N-diphenyl hydrazine,

also exhibits remarkable anti-oxidant powers The relative rates of aging.

in rubber, as is evident from the following table: v v

Aging tests of diam-s ll di'pheng lhydrazine After 7 days After 48 hours Before aging in the Geer i111) the Igicreg- 0 on a s om Age-resistor (0. 5%) H T E '1 E '1 E None (control) 3540 G63 2196 4T0 642 '26s Diani syl diphenyl i.

hydrazine 3303 663 3150 577 2564 573 Emample .4. The effect of the tetra-substituted hydrazines is most marked when all four substituent groups comprise p-substituted benzene nuclei. For example, tetra-ptolyl hydrazine,

.N-N GHQ Oom gives the following results:

Aging tests of tetra-p-tofyl hydrazine From the above data it is evident that the tetra-substituted hydrazines are excellent age-resisters in rubber. The tetra-aryl hydrazincs, in particular, are so active ageresisters that a-composition containing only 0.5% undergoes substantially no deterioration when subjected to an accelerated aging test which almost completely destroys the strength of the same composition without the tetra-aryl hydrazine. However, it is to be understood that the examples are merely illustrative, and that the tetra-substituted hydrazines may be incorporated into rubber compositions of the most various nature with good effect upon their age-resisting properties. They may also be applied-to unvulcanized or vulcanized rubber with good effect on the age-resisting properties of the rubber, such as by applying them to the surface of the rubber, as for example in solution, or in the form of a paste or emulsion.

It is to be understood that the term treating as employed in the appended claims is used in a generic sense to include either the incorporation of the age-resisters into the rubber-by milling or similar process, or their addition to the rubber latex before its coagulation, or to the-application thereof to the surface of a mass of crude or vulcanized rub her. The term rubber is likewise employed in the claims in a generic'sense to include caoutchouc, whether natural or synthetic, re-

claimed rubber, balata, gutta percha, rubber isomers and like products, whether or. not admixed with fillers,- pigments, vulcanizing or accelerating agents. While I have herein disclosed certain preferred manners of performing my invention, I do not thereby desire or intend to limit my: self solely thereto, for, as hitherto stated, the precise proportions of the materials utilized may be varied and other materials having equivalent chemical properties may be em t ployed if desired without departing from the spirit and scope of the invention as defined in.

.the appended claims. I I

I claimi 1. The method of preserving rubber which comprises treating rubber with a tetra-substituted'hydrazine. g

2. The method of preserving rubber which comprises treating rubber with a tetra-sub comprises treating rubber with tetraphenyl hydrazine.

7. The method of preserving rubber which comprises incorporating tetraphenyl hydrazine into rubber before vulcanization.

\ 8. The method of manufacturing an ageresisting rubber product which comprises incorporating a tetra-aryl hydrazine into a vulcanizable rubber composition, and vulcanizing the composition.

9. An age-resisting rubber product com- I prising rubber and a tetra-substituted hydrazine.

10. An age-resisting rubber product com- 13.'An age-resisting rubber composition comprising a substance selected from the class comprising tetraphenyl hydrazine and substitution productsthereof, the substituents being aliphatic hydrocarbon radicals.

14. An age-resisting rubber composition comprising tetraphenyl hydrazine.

15. An age-resisting rubber product resulting from the vulcanization of a composition comprising rubber, sulphur, an accelerator, and a tetra-substituted hydrazine.

16, An age-resisting rubber product resulting from the vulcanization 01' a composition comprising rubber, sulphur, an accelerator,

and a tetra-aryl hydrazine.

17. An age-resisting rubber product resulting from the vulcanization of a composition comprisin rubber, sulphur, an accelerator, and tetrap enyl hydrazine.

In witness whereof I have hereunto set my hand this 17th day ofJanuary, 1929.

. 7 PAUL C. JONES.

, prising rubber and a tetra-substituted hydrazine, the substituent groups comprising aromatic nuclei.

11. Anage-resisting rubber composition comprising rubber and a tetra-aryl hydrazine.

12. An age-resisting rubber composition comprising rubber and a substance selected from the class comprising tetraphenyl hydra 65 zineand substitution products thereof. 

